In the United States, it is estimated that 63% of cases are solved, however that leaves 37% that are left unsolved. In violent crimes alone, the U.S. suffered over 1 million cases, of which almost half were left cold (FBI, 2010). A number of unsolved cases remain that way because of the lack of evidence, such as DNA at the crime scene. I intend to use the bacterial strains found in bite marks of victims to match the marks to the biter by comparing the strains found in each location. The bacteria amplified, using Polymerase Chain Reaction, and allow for a comparison between the various strains that should be found. From this, I will be able to suggest that bacteria found in wounds at the scene of a crime can be used to determine suspects.
There are three main points that need to brought into perspective The first is to test the saliva from each bacteria to determine that their bacterial strains aren’t the same genotype. The main bacterial type found in the human mouth is streptococcus (Kennedy 2011); assuming that is true in the cases of the volunteers, it is assumed that the bacterial strains of streptococcus found on the teeth and in saliva will be transferred to the skin of the victim as well. Though streptococcus is typically the most predominant strain found in the oral cavity, for the purpose of this study, the most predominant bacteria found in the volunteers of the experiment is what will be used in the results. The second is that the bacteria will survive long enough on the skin and survive the duration of the experiment. The last aim is to perform PCR and see if the bacteria, once amplified can be matched back to the person who it came from.
With these three points, I hope to prove that bacteria left on a bite mark victim can be amplified and used as a comparison technique in order to find a suspect in the case. I will use human volunteers to provide the necessary information needed for the experiment. Each will, hopefully, house different bacterial strains in order to provide data for comparison.
Specific Aim 1: I will swab the teeth and saliva of each volunteer. The bacteria will then be swabbed onto plates containing nutrient agar in order to view the various bacteria and the most common. The volunteer’s will bite their bicep, long enough to the point they can stand the pain. After an hour, I will return and swab the bite mark.
Specific Aim 2: I will have a third party bite the impression putty and let it sit over night. I will also swab their teeth and saliva for analysis. I will immediately plate the swab and incubate it to see the number of colonies present and to identify the most common bacteria strain found. After 24 hours have passed, I will swab the impression, plate it, then view the number of bacterial colonies that appear after 24 hours, determining the most prominent strain present. Finally, I will compare the results to the number of bacteria colonies that developed from swabbing the...